Recovering from Usual Attitudes at Unusual Airspeeds

Given an airplane's natural tendency to enter a descending turn — a spiral — recovering to level flight shouldn't be thought of as an unusual maneuver. But an airplane in a spiral also builds speed — rapidly. According to AVweb contributor R. Scott Puddy, the skill pilots need to perfect is not recovering from unusual attitudes but recovering from usual attitudes at unusual airspeeds.

By R. Scott Puddy
| August 14, 2000

Related Articles

About the Author ...

R. Scott Puddy was an ATP, CFI, CFI-I, MEI who taught out of the
Buchanan Field Airport (CCR) in Concord, California. Scott was type-rated
in the Beech/Raytheon King Air 300 series but regularly flew a V35 Bonanza
and practices law in San Francisco.

On the morning of June 18, 2002, Scott perished doing what he
loved: practicing aerobatics in a Yak-52, in the mountains of Brentwood,
California.

He contributed many articles about flying to AVweb in recent
years and also worked as our features editor. His enthusiasm for
aviation and his intensity in pursuing it were simply extraordinary.
Even more extraordinary was his dedication to sharing his passion for
flying with others, by teaching and writing. He touched a lot of lives,
undoubtedly saved many, and his legacy of written words will continue
to do both for many years to come. Scott's warmth, wit, and keen
intelligence will be missed by all who knew him and worked with him.

The
designation "unusual" connotes something that is either
unexpected or extraordinary. Leave it to the FAA to slap the label
"unusual" on an event that is predictable and routine. If
you leave an airplane to its own devices, it will enter a descending
turn. If airspeed is not a consideration, recovering from a descending
turn requires merely that you roll to wings level and pitch for level
flight. We've all done it a thousand times. However, if the airspeed
indicator is advancing beyond Vne while you are descending and
turning, the flight regime would indeed qualify as
"unusual." Speed kills and we do not accumulate a lot of
practice time flying at airspeeds in excess of Vne. The skill we need
to perfect, without the benefit of any practical opportunity to
practice it, is not "recovery from unusual attitudes" but
rather "recovery from usual attitudes at unusual airspeeds."

The Predictable Spiral

In his recent AVweb article "The
Deadly Spiral," Paul A. Soderlind made the convincing case that an
airplane's ultimate equilibrium flight state is the spiral dive. I will not
repeat his analysis, but will report the results of my own empirical testing
of Mr. Soderlind's theory. The table below reflects the various conditions I
encountered in 20 attempts at protracted hands-off flight:

Spiral

Stall

Spin

Inverted
Spin

Snap
Roll

Tail
Slide

Split-S

Reverse
Cuban 8

20

0

0

0

0

0

0

0

Try it yourself. Feel free to invent your own categories.

In another recent AVweb article, "Training
at FlightSafety," Mike Busch reported that his FlightSafety
instructor had succeeded in inducing inverted flight during a simulator-based
unusual attitude recovery exercise. That is all great sport, and it is fun to
imagine what the instrument indications would be if you were unexpectedly to
encounter a truly aerobatic flight regime (e.g., a tail slide) in IMC.
However, in training for the real world you need to play the odds. The
overwhelming odds are, if you have failed to pay the airplane the attention it
deserves and the instrument indications are awry when you look back at the
panel, you are in a spiral dive. That is the condition you should expect and
is the principal condition you should train for.

When Spirals Become "Unusual"

It is not the pitch angle or bank angle that makes a spiral dive
"unusual." Since there is no redline on the attitude indicator, you
can fly an airplane through a 360-degree range in bank (a roll) or pitch (a
loop). Airspeed is another story, which is why airspeed indicators are marked
so colorfully with red lines, blue lines, white arcs, green arcs, yellow arcs,
and so on. Although a plane will fly at any attitude, it cannot be counted
upon to fly at 1.5 Vne or .8 Vso.

Airspeed can quickly get out of control in a spiral dive, leading to a
flight regime that is without question "unusual." One such event is
the subject of a recent
NTSB report which begins: "On July 16, 1999, about 2141 eastern
daylight time, a Piper PA-32R-301, Saratoga II, N9253N, was destroyed when it
crashed into the Atlantic Ocean approximately 7 1/2 miles southwest of Gay
Head, Martha's Vineyard, Massachusetts."

N9253N was descending into Martha's Vineyard and was established on an
easterly course, descending through 2,600 ft. msl at approximately 900 fpm.
Power was set for a cruise descent yielding approximately 160 KIAS. At
2140:15, N9253N began to bank to the right at a nearly constant rate. In the
next 10 seconds, the bank angle reached 45 degrees. The flight path was five
degrees down. The bank and pitch angles continued to increase thereafter at a
constant rate until, 35 seconds later, N9253N impacted the water at a bank
angle of 125 degrees, a nose-down pitch attitude of approximately 30 degrees,
and a descent rate in excess of 4,700 fpm. The instrument indications on the
airspeed indicator and vertical speed indicator were at their maximum positive
mechanical limits and the engine was developing full takeoff power. The
transition from "usual" to "unusual" required but 45
seconds and there was no recovery in this instance.

Yes, this was the crash that killed John F. Kennedy Jr., his wife and his
sister-in-law.

Speed Kills

Flight at extreme airspeeds can cause an in-flight breakup and, in the case
of a high-speed dive, can prolong recovery leading to impact with terrain. Put
simply, speed kills. More precisely, excessive airspeeds can dramatically
diminish your prospects for survival. It is important to understand the risks
of excessive speeds. It is equally important to understand that you may have a
chance of surviving an unintended venture into the world of flight beyond Vne
if you respond appropriately.

Airspeeds
in excess of those specified in the "Limitations" section of the
Pilot's Operating Handbook (POH) generally do not take apart an airplane in
the manner that the Big Bad Wolf disassembled the little pig's house of straw.
Rather, flight at those airspeeds limits the plane's ability to survive
specific flight conditions. If those flight conditions do not arise during
your period of transgression, you may survive. If they do, you may perish. In
order to maximize your chances of survival, you need to understand these
conditions and devote some thought to how you should recover from an overspeed
situation.

Full, Abrupt Control Movements

For a Beech Bonanza (BE-V35), maneuvering speed (Va) is 134 KIAS at full
gross weight (3,400 pounds) and represents the airspeed beyond which the pilot
should not use full, abrupt control movements (FACMs). That is because 134
KIAS is the airspeed at which the wing is first capable of generating 12,920
pounds of lift or 3.8 Gs (3,400 x 3.8 = 12,920). The positive design load
limit for normal category general aviation aircraft is 3.8 Gs. If you were to
pull sharply back on the controls at an airspeed above Va, the wing might
accelerate the aircraft at an excessive rate.

Below gross weight, Va decreases because it takes less force to accelerate
a lighter object at a rate of 3.8 Gs. The test data for this article was
generated at a gross weight of 2,800 pounds. At 2,800 pounds, Va would be
121.6 KIAS (134 x sq. rt.(2,800 / 3,400) = 121.6). However, at 2,800 pounds,
the aircraft would be loaded within the certified limits in the utility
category. The positive design load limit for the utility category is 4.4 Gs.
At 2,800 pounds, the airplane could exceed 4.4 Gs at airspeeds above 131 KIAS.

Although we pilots are not allowed to rely on this, the designers also add
a safety factor of 1.5 so that the ultimate load factor is 1.5 x 3.8 or 5.7 Gs
(normal) and 1.5 x 4.4 or 6.6 Gs (utility). At full gross weight, you could
exceed the 5.7 ultimate load factor (normal) at airspeeds above 164 KIAS. Our
lighter 2,800-pound test aircraft could exceed the 6.6 G ultimate load factor
(utility) at airspeeds above 160 KIAS.

So, what does
all that mean in terms of your chances of survival? In a 3,400-pound V35,
FACMs at airspeeds below 134 KIAS should not lead to injury to you or damage
to the plane. The airplane was originally designed so that its essential
components would remain intact in the event of FACMs at airspeeds between 134
KIAS and 164 KIAS, although the airplane would be expected to suffer damage.
However, some of the airplane's components may have been fatigued by prior
events or the metallurgy of a key fastener may have been a little off-spec. It
might not be your lucky day. At airspeeds over 164 KIAS, FACMs would demand
performance from the airplane that its designers never contemplated. You would
not survive unless it truly was your lucky day.

To place those G-force values in context, a 3-G pull is an aerobatic
maneuver that will wear you out. Normal people "grey out" (suffer
from loss of vision) after several seconds' exposure to 4 Gs. Normal people
"black out" (lose consciousness) after several seconds' exposure to
6 Gs. If you were abruptly to pull back on the yoke, you could easily expose
the airplane to excessive Gs without feeling the impact of what you're doing
to yourself and the airplane. If you apply back force more gradually with the
thought that, if you're feeling the effect of too much G-force then the force
on the plane is probably excessive as well, you will have a much better chance
of surviving the experience.

Mother Nature's Control Inputs

Next of concern are the airspeeds at which airplanes are designed to
survive MNCIs (Mother Nature's Control Inputs). An MNCI arrives in the form of
vertical gusts of wind. Total lift is a function of airspeed and angle of
attack. At cruise flight at 151 KIAS, our test airplane would be capable of
generating 4.8 Gs. However, the pilot maintains the 1 G necessary to sustain
level flight by commanding a minimal angle of attack with the elevator.
Problems could arise if Mother Nature serves up a vertical gust of wind. The
vertical gust changes the angle of the relative wind which in turn causes an
uncommanded increase in the angle of attack and a corresponding increase in
lift. In turbulence we feel the increase and decrease in the wing's lift, not
the physical impact of wind gusts on the structure of the airplane.

Off the top end of the V-G diagram is design dive speed (Vd). General
aviation aircraft are capable of withstanding vertical gusts of +/- 15 fps at
Vd which is at least 1.4 Vc (Normal) or 1.5 Vc (Utility). In a V35, the Vc of
156 KIAS requires that Vd be at least 218 KIAS (normal) or 234 KIAS (utility).
Design dive speed can also be estimated based upon the published Vne value.
Never exceed speed cannot exceed 0.9 Vd. Vne for the V35 is 196 KIAS. Vd must
therefore be at least 218 KIAS.

It would
be neither legal nor sane to exceed Vne intentionally. However, if ever find
yourself unwittingly in that position, take some comfort in knowing that some
pilot was there before you and lived to certify the event. You, too, could
survive if you play your cards right. In the context of unusual airspeeds that
means understanding that the airplane will give you the same G-force
performance right up to Vne and beyond. However, the plane is fragile at high
speeds because of the much greater potential of exceeding the design G-loads.
At its 218 KIAS design dive speed, a 3,400 pound V35 would be capable of
generating 10 Gs. At its 234 KIAS design dive speed (utility), our 2,800 pound
test plane would be capable of generating 14 Gs. One FACM and you're toast.
Moreover, although the plane will withstand a 15 fps vertical gust, if you
happen across a 40 fps MNCI you are likewise toast. The moral: Go EASY on the
pitch control and pray for smooth air until you get the plane slowed down to
an airspeed that registers on the airspeed indicator.

Acceleration And Vertical Acceleration

It is reassuring to imagine being able to hit 234 KIAS in a spiral dive
and, drawing upon your superior piloting skills, being able to slowly coax the
airplane back into a cruise configuration. Before that warm and fuzzy feeling
becomes overwhelming, let's consider the box that a high-speed spiral creates
for the unfortunate pilot.

Airplanes accelerate whenever thrust exceeds drag. As pitch angles
increase, the component of the gravitational force along the airplane's line
of flight increasingly assists the engine in developing thrust. Airspeed
increases rapidly. Worse yet, a component of airspeed is in a vertical
direction which means that vertical speed increases as a function of both
airspeed and descent angle. Astounding vertical descent rates can arise at
seemingly benign descent angles.

The table below shows calculated terminal velocities and rates of descent
for a V35 Bonanza in various configurations. (I will post the entire table and
address questions about methodology in AVweb's threaded
messages area if anyone is interested.) If you are flying a late-model
Mooney or Lancair, the values would be even higher. If you are flying a Cessna
172, the numbers would be less severe.

Descent
Angle (Deg.)

100%
Power, Gear Up

75%
Power, Gear Up

Idle
Power, Gear Up

Idle
Power, Gear Down

10

213 KIAS
3,748 fpm

194 KIAS
3,414 fpm

121 KIAS
2,129 fpm

90 KIAS
1,584 fpm

30

270 KIAS
13,680 fpm

256 KIAS
12,972 fpm

206 KIAS
10,438 fpm

153 KIAS
7,753 fpm

45

301 KIAS
21,570 fpm

288 KIAS
20,638 fpm

245 KIAS
17,556 fpm

182 KIAS
13,042 fpm

As you can see, these are big numbers. It should also be apparent that, at
any given angle of descent, flying at an excessive airspeed imposes a
substantial descent rate penalty. Finally, you pay a substantial penalty in
terms of airspeed and rate of descent if you do not take the proper steps to
reduce thrust and increase drag.

The Recovery Box

Airplanes that are designed to chew up air miles can rapidly digest
altitude when they are pointed downhill. In the extreme case noted above, if
you are passing through 7,000 feet at a descent rate of over 21,000 fpm,
impact is less than 20 seconds away. You have to recover quickly but the
airplane will disintegrate if you make a sudden move. The odds aren't good.

Less obvious is the impact of high vertical speeds on the time that will be
required to recover because of vertical inertia. If the available force to
decelerate an object is constant, the recovery time increases in proportion to
the established velocity.

Acceleration x Time =
Velocity and therefore Time = Velocity/Acceleration

In recovering from a high-speed dive, physiological constraints and
structural limits restrict the available lifting force. Therefore,
acceleration is a fixed value and recovery time will increase in direct
proportion to the vertical descent rate. Recovery from a 20,000 fpm rate of
descent will take about ten times as long as recovery from a 2,000 fpm rate of
descent. At high airspeeds, you may not have enough time to recover even if
you can succeed in holding the airplane together.

Control Your Airspeed!

For all the above reasons, the first order of business in a high-speed
spiral is to control your airspeed. Airplanes accelerate for the simple reason
that thrust exceeds drag. In order to keep airspeed under control you need to
minimize thrust and maximize drag. In any airplane, the first step is to chop
the power. In some planes you can further increase drag by dropping the gear,
moving the propeller control to a high rpm setting, and/or deploying speed
brakes. Leave the flaps retracted. The last thing you need at this stage is
asymmetrical flap deployment.

Let's see what Beechcraft has to say. The POH for the V35 Bonanza doesn't
address recoveries from a spiral dive but does contain a section entitled
"Emergency Speed Reduction." According to Beechcraft:

"In an emergency,
the landing gear may be used to create additional drag. Should
disorientation occur under instrument conditions, the lowering of the
landing gear will reduce the tendency for excessive speed build-up.
This procedure would also be appropriate for a non-instrument rated
pilot who unavoidably encounters instrument conditions or in other
emergencies such as severe turbulence."

"Should the landing gear be
used at speeds higher than the maximum extension speed [145 KIAS], a
special inspection of the gear doors in accordance with shop manual
procedures is required, with repair as necessary."

Beechcraft is telling us is that, at unusual airspeeds, we will start
losing the wings before landing gear components (except for the gear doors) if
the gear is lowered at airspeeds in excess of 145 KIAS. Easy enough to
complete a flight safely with a bent gear door (just leave the gear down,
please). Not so easy to complete a flight missing parts of the tail.

In a V35 in a 30-degree descent, if you chop the power and drop the gear
you'll decelerate to 153 KIAS (0.9 Vno) at a 7,753 fpm descent rate. Leave the
gear up and the power in and you'll be flying at 256 KIAS (1.3 Vne / 1.17 Vd)
and descending at 13,000 fpm. Add full power and you'll be at 270 KIAS (1.4
Vne / 1.24 Vd) and hurtling downward at 13,700 fpm.

Your options for controlling airspeed will vary from plane to plane. If the
gear is fixed, dropping the gear is not an option. If you are accelerating
through Vne in a C-182RG or a PA28R-201T you have the option of selecting gear
down, but should you? I haven't researched all makes and models. You need to
determine that answer yourself for the planes you fly.

But, In A 13,000 FPM Descent, Don't I Need Full Power To Climb?

Do not increase the power setting simply because you are experiencing a
high rate of descent. If you are hurtling toward Mother Earth at airspeeds in
excess of Vne you have available climb power in spades — it's called
"inertia." Thinking about it in another way, although power is
required to sustain a climb in unaccelerated flight, a wing's capability of
generating lift is merely a function of airspeed. In plain English, this means
that you can generate as much lift as you want if you have excess airspeed to
trade. The airplane will simply decelerate. If you are traveling at a speed in
excess of Vne, deceleration is a good thing, not a bad thing. When the
airspeed slows to the point that lack of power becomes a concern, add power.

Let's attach some number to that proposition. At 2,800 pounds, Va for the
test plane is 122 KIAS. By definition, the wing is capable of generating 3.8
Gs at Va. Depending on the loading, the Bonanza is also rated in the utility
category (4.4 Gs). You pass out at 6 Gs. The ultimate load limit is 6.6 Gs.
The airspeeds of concern, therefore, are:

Desired
lift:

3.8 Gs

4.4 Gs

6 Gs

6.6 Gs

Required
Airspeed:

122 KIAS

131 KIAS

153 KIAS

160 KIAS

What this means is that, if you are descending toward Mother Earth at 256
KIAS, you will be capable of generating sufficient lift to break the airplane
until the airspeed decays below 160 kts, sufficient lift to render yourself
unconscious until airspeed decays below 153 KIAS, and sufficient lift to
exceed the positive design load limit of the airplane until the airspeed
decays below 131 KIAS. Absence of power to sustain a climb is not one of your
immediate concerns. By the time insufficient power becomes a concern, the
world will be moving much more slowly. CHOP THE POWER!

Coffee-Table High-Speed Spirals

As mentioned above, unless you have access to a full motion simulator, you
will not have a practical opportunity to practice recoveries from unusual
airspeeds. You can't perform them in an airplane. You have to rehearse them
with your feet on your coffee table. Let's walk through one.

Here's the situation: You are in cruise in IMC and are attempting to insert
the approach plate into the yoke clip when it slips through your fingers and
flutters to the floor. "Where did it go?" You finally gather the
plate from the floor in front of your rear seat passenger and glance back at
the panel only to be confronted by a slew of aberrant instrument indications.

Step 1: Control Your Airspeed

You understand that airspeed is your mortal enemy so you direct your
attention first to the airspeed indicator. The airplane is accelerating
through Vne so you immediately chop the power and take whatever additional
steps may be appropriate to increase the parasite drag for the specific plane
you are flying (e.g., gear down, prop forward, speed brakes deployed).

Step 2: Roll To Wings Level

Look at the turn coordinator and apply coordinated aileron and rudder
inputs opposite to the indicated direction of turn until your wings are level.
Do not rely on the attitude indicator. Its indications may be confusing in an
extreme attitude and a failed attitude indicator is a likely cause of your
present predicament in the first place. The turn coordinator gives you a
simple indication of whether you are turning to the left or to the right. If
you're turning left, use control inputs for a right turn. If you're turning
right — vice versa.

Leave pitch alone while you are correcting the bank. In a steep bank, a
pitch up control input would only tighten the turn. In a very steep bank (over
90 degrees), you are partially inverted and a pitch up control input would
actually increase your (inverted) descent. Finally, in a steep bank, the
G-forces are distributed unequally on the wings which imposes greater stresses
on the airframe.

Step 3: Recover From The Dive

The airplane is trimmed for straight-and-level flight so, once the wings
are level at your substantially higher airspeed, it will be inclined to pitch
up dramatically. Do not haul back on the yoke. You may actually have to use
forward pressure initially to keep G-forces under control. Make slow pitch
inputs so that you can experience the physiological effect of the G-forces
before they get out of hand, remembering that the effects you feel roughly
correspond to the forces that the airplane can withstand. If your eyesight is
fading to gray, the forces are around 4 Gs or so and it's time to release a
little back pressure.

Whew! You made it! Every GA pilot alive has dreamt of being called to the
cockpit of a 747 to bring it down after the flight crew succumbed to the
effects of a fish fry. The next time those thoughts start to come to mind,
think instead about how you might coax your four-seater down from Vd to Vno.
It is a situation that is equally perilous and substantially more probable. In
this context, a little daydreaming might actually save your life.